Copper base alloy



Patented Jam 3, 1939 vu NlTizn STATE COPPER BASE ALLor 1 Franz n. Hensel and Earl I. Lmemjlnaianapoiis,

Ind., assignors to Il. Indianapolis, 1nd., a

E. Mallory & Co., Inc.,

corporation of Delaware Application November. 9,1936, serial No. 109,906

l 1 Claim.

'I'his invention relates to copper base alloys, the

- present. application comprising a continuation in part of our copending application, Serial No.

I90,865, filed l'illy 16, 1936, Since matured into Pat'- ent No. 2,123,629, dated July l2, 1938. A A11-object of the invention is to produce an improved copper base alloy.

` A-further object is -to provide` an alloy, the physical properties of which can be improvedby heat treatment.

An additional object of the invention is to im-` prove the hardness and other characteristics of a precipitation hardened copper alloy. I J

Other objects of the 'invention will 'be apparent from-the following description taken in connection with the appended claim.

The present inventioncomprises the combination of elements, methods of manufacture, and the product thereof brought out and exemplified inthe disclosureK hereinafter set forth, the sco of the invention being indicated in the appendo claim.

`ing the age hardening of an alloy While a preferred embodiment of the invention is described herein, it is contemplated that considerablevarlation may be made in the method of procedure and the combination of elements without departing from the spirit of the invention.

The invention may be better understoodfrom the following description when read in conjunction with the accompanying drawing in which: The gure is a graph illustrating the improvement in hardness and conductivity obtained durmade according to the present invention as compared with another alloy..

The present invention relates to an improved copper base alloy containing cobalt, phosphorus and silicon. It has been found that by adding cobalt and phosphorus to copper an intermetallic compound of cobalt phosphide can be formed which has a variable solid solubility in the copper matrix. We have discovered that the addition of silicon improved these alloys, the improvement in means.

hardness and electrical conductivity obtained'by the additions of silicon being accentuated byv a suitable age hardening process.

The alloy may be produced as follows:

' -Copper is melted under glass or charcoal slag and superheated. A hardener containing 75% cobalt and 25% copperis added as a convenient means to incorporate cobalt. yThe silicon may be similarly added. Phosphorus is then added in the form of phosphor copper or some other suitable In the molten condition, the alloy is extremely fluid and pours very easily. j

The proportions of cobalt and phosphorus may each be varied over a considerable range of values and there may be an excess of either in some instances without deleterious eiects on thev alloy. The preferred weight ratio of phosphorus to cobalt is approximately'l to 6.' However, considerable age-hardening is obtained with the ratio of l to 3 and also with a ratio as high as 1 to 10.

A slight excess of phosphorus above the amount required to form certain lntermetallic compoundsof cobalt phosphide will ordinarily serve as a'deoxidizing agent during the production of the alloy.

The cobalt phosphide is suitable as an age hardening ingredient for copper or certain copper alloys. The silicon produces additional beneficial effects in this regard. W

Where the cobalt, phosphorus and silicon are 20 added to copper the ingredient may be present in the following permissible ranges of proportions:

After 'the alloy has been produced it may be heated to a relatively high temperature above '100 C. and preferably in' the order of 800'C. to

1000o C. and then rapidly cooled from that tem- 40 temperature or below, preferably byrquenching in water. After the quenching operation the alloy, in such form as may be desired, may be given an aging treatment by baking perature to room at a temperature below 700 C. and preferablyat 45 a temperature in the' order of 350 C. to 650 C. A The aging may' proceed for a considerable length of time according to the' temperature used. The most rapid improvement in hardness and electrical conductivity will beobtained during the first two or three hours if 450 C. is used asr aging temperature but further improvement will be obtained upon continuing the aging for 8 to 16 hours or more. y

The improvement in hardness and electrical son alloy are the same with silicon is absent. l5

conductivity during aging is shown in the graphs of the ligure i'or a representative alloy made according to thepresent invention in comparison with analloy o! similar composition except ior the absence of silicon. The representative alloy has the following composition:

Percent Cobalt 2.37 Phosphorus 0.63 Silicon 0.25 Copper Balance The proportions of ingredients in the compariafter aging for 8 For more hours at 450 C. Curve Il represents the increasev in hardness of the representative alloy given above containing 0.25% silicon. It will be noted that the hardness of 'the silicon-containing alloy, while initially less eventually reaches a higher value than the hardness of the alloy without silicon. 'I'he hardness of the silicon-containing alloy increases from about 24 Rockwell B immediately after quenchingto about74 Rockwell B after aging for about 16 hours.

Curve I2 in the figure represents the improvement in electrical conductivity of the comparison alloy during the age hardening treatment. It

will be noted that the conductivity increased from about 27% ofthat of copper after quenching to 55 or 56% after aging for 4 or more hours. Curve I 3 represents the increase in conductivity of the alloy containing 0.25% silicon. It will be noted that the conductivity of the silicon-containing alloy is somewhat greater regardless of the aging time, the conductivity increasing from about 31% of that of copper after quenching to above 64% after aging about 16 hours. While the comparison alloy containing no silicon exhibited little change in hardness or conductivity after 4 to 8 hours aging the siliconcontaining alloy increased considerably in hardness upon further aging, the maximum being reached after aging for more than 16 hours.

By varying the proportions of the ingredients in the alloy, it is possible to obtain even higher electrical conductivity -and hardnesses.

After the aging treatment the material may be cold worked by rolling, for example. The hardness will be increased by cold working while t e ,electrical conductivity is not materially changed thereby.

The alloy of the present invention is able to withstand high temperatures without losing its hardness or high conductivity. 'I'he hardness and conductivity of the age-hardened alloy may be maintained at temperatures considerably above the aging temperatures used and'that of the cold Worked alloy may also be maintained at relatively high temperatures such as at 400 C. or greater.

The present alloy is easy to produce. In pourthe exception that ing the alloy it shows a clean stream and great iiuidity.

No dimculty due to cracking or checking is encountered in hot rolling and cold working of this alloy.

.In the binary copper-cobalt system the solubility .oi cobalt in copper decreases with decreasing temperature, ,the cobalt being soluble in copper in the solid st ate only to a very liniited extent. At 1000" C. 3.5% cobalt is held in solid solution by copper. At 600 C. only 0.9% cobalt is held in solid solution and at room temperattuzse this percen age decreases to approximately By adding phosphorus, cobalt phosphide is formed and this compound has a lower solid solubility in copper than does cobalt. The precipitation hardening eil'ect is therefore greater. In age hardened alloys the hardening ingredients greatly decrease the electrical conductivity to the extent in which they are held in 'solid solution. Cobalt phosphide, therefore, produces a higher electrical conductivity for the same amount of hardening than does straight cobalt since less of the phosphide is held in solid solution.

Another advantage accruesii'romwthe fact that the precipitated phase, consisting of cobalt phosphide or copper cobalt phosphide has in itself asubstantial hardness. The hardness of this phase is much greater than the precipitated electrodes because of its combination of high -phase in binary copper-cobalt alloys. This makes hardness and electrical conductivity. This results in greater freedom from mushrooming in service. The electrodes are well adapted for the welding of terne and tin plate.

The alloy also makes excellent soldering iron tips due toits freedom from intercrystalline penetration of liquid metals. We have found it superior in this respect to most of the present copper base alloys.

high electrical conductivity combined with high strength and hardness at room or elevated temperature isrequired.

ing that the silicon makes possible alloys of considerably greater hardness and surprisingly, the silicon also appears to improve the electrical conductivity. i

While the present' invention, as to its objects .and the like composed of an alloy containing about .05 to 5% cobalt, .01 to 2% phosphorus, .01 to 1% silicon and the remainder substantially all copper.

FRANZ R. HENSEL. EARL I. LARSEN.

It is apparent from the curves of the' draw- -59- I The alloy is .likewise well adapted to other applications where the combination of relatively" 

